Physics: Projectile Motion, Momentum, Work, and Doppler Effect

This set of vocabulary flashcards covers essential definitions and concepts for Vertical Projectile Motion, Linear Momentum, Work-Energy, and the Doppler Effect for sound and light.

Free fall (projectile motion)

The motion of an object under the influence of the force of gravity only.

Projectile

An object that is launched with an initial velocity and upon which the only force acting is the force of gravity.

Acceleration of Free Fall

During the motion of a projectile, the acceleration is $9,8\,ms$ downwards at any point.

Momentum

A vector quantity defined as the product of an object's mass and its velocity ($p = mv$).

Newton's second law of motion (in terms of momentum)

The resultant/net force acting on an object is equal to the rate of change of momentum of the object in the direction of the resultant/net force.

Impulse

The product of the resultant/net force acting on an object and the time the resultant/net force acts on the object ($F_{net}\Delta t$).

Isolated system

A system on which the resultant/net external force is zero.

Principle of conservation of linear momentum

The total linear momentum of an isolated system is conserved.

Elastic collision

A collision in which total kinetic energy is conserved, meaning the sum of kinetic energy ($E_k$) before equals the sum of $E_k$ after.

Inelastic collision

A collision in which total kinetic energy is not conserved because energy is transferred as heat, sound, or light.

Work

The work done on an object by a constant force $F$ is calculated as $F\Delta x\cos(\theta)$, where $F$ is the magnitude of the force, $\Delta x$ is the displacement, and $\theta$ is the angle between the two.

Joule (J)

The unit of measurement for work done, which is a scalar quantity.

Doppler Effect (sound)

The apparent change in frequency (pitch/wavelength) of a sound detected by a listener as a result of the relative motion between the source of the sound and the listener.

Frequency

The number of wave pulses per second.

Period

The time taken for one complete wave pulse.

Wavelength

The distance between two successive points in phase.

Doppler flow meter

A medical instrument used to measure the rate of blood flow using the Doppler effect.

Doppler Foetal monitor

A medical instrument used to detect foetal heartbeat using the Doppler effect.

RED Shift

The shift of light towards the red end of the spectrum (increase in wavelength / decrease in frequency) that occurs when a star moves AWAY FROM Earth.

BLUE Shift

The shift of light towards the blue end of the spectrum (decrease in wavelength / increase in frequency) that occurs when a star moves TOWARDS Earth.